revision.c

   1 #include "cache.h"
   2 #include "tag.h"
   3 #include "blob.h"
   4 #include "tree.h"
   5 #include "commit.h"
   6 #include "diff.h"
   7 #include "refs.h"
   8 #include "revision.h"
   9 #include "graph.h"
  10 #include "grep.h"
  11 #include "reflog-walk.h"
  12 #include "patch-ids.h"
  13
  14 volatile show_early_output_fn_t show_early_output;
  15
  16 static char *path_name(struct name_path *path, const char *name)
  17 {
  18         struct name_path *p;
  19         char *n, *m;
  20         int nlen = strlen(name);
  21         int len = nlen + 1;
  22
  23         for (p = path; p; p = p->up) {
  24                 if (p->elem_len)
  25                         len += p->elem_len + 1;
  26         }
  27         n = xmalloc(len);
  28         m = n + len - (nlen + 1);
  29         strcpy(m, name);
  30         for (p = path; p; p = p->up) {
  31                 if (p->elem_len) {
  32                         m -= p->elem_len + 1;
  33                         memcpy(m, p->elem, p->elem_len);
  34                         m[p->elem_len] = '/';
  35                 }
  36         }
  37         return n;
  38 }
  39
  40 void add_object(struct object *obj,
  41                 struct object_array *p,
  42                 struct name_path *path,
  43                 const char *name)
  44 {
  45         add_object_array(obj, path_name(path, name), p);
  46 }
  47
  48 static void mark_blob_uninteresting(struct blob *blob)
  49 {
  50         if (!blob)
  51                 return;
  52         if (blob->object.flags & UNINTERESTING)
  53                 return;
  54         blob->object.flags |= UNINTERESTING;
  55 }
  56
  57 void mark_tree_uninteresting(struct tree *tree)
  58 {
  59         struct tree_desc desc;
  60         struct name_entry entry;
  61         struct object *obj = &tree->object;
  62
  63         if (!tree)
  64                 return;
  65         if (obj->flags & UNINTERESTING)
  66                 return;
  67         obj->flags |= UNINTERESTING;
  68         if (!has_sha1_file(obj->sha1))
  69                 return;
  70         if (parse_tree(tree) < 0)
  71                 die("bad tree %s", sha1_to_hex(obj->sha1));
  72
  73         init_tree_desc(&desc, tree->buffer, tree->size);
  74         while (tree_entry(&desc, &entry)) {
  75                 switch (object_type(entry.mode)) {
  76                 case OBJ_TREE:
  77                         mark_tree_uninteresting(lookup_tree(entry.sha1));
  78                         break;
  79                 case OBJ_BLOB:
  80                         mark_blob_uninteresting(lookup_blob(entry.sha1));
  81                         break;
  82                 default:
  83                         /* Subproject commit - not in this repository */
  84                         break;
  85                 }
  86         }
  87
  88         /*
  89          * We don't care about the tree any more
  90          * after it has been marked uninteresting.
  91          */
  92         free(tree->buffer);
  93         tree->buffer = NULL;
  94 }
  95
  96 void mark_parents_uninteresting(struct commit *commit)
  97 {
  98         struct commit_list *parents = commit->parents;
  99
 100         while (parents) {
 101                 struct commit *commit = parents->item;
 102                 if (!(commit->object.flags & UNINTERESTING)) {
 103                         commit->object.flags |= UNINTERESTING;
 104
 105                         /*
 106                          * Normally we haven't parsed the parent
 107                          * yet, so we won't have a parent of a parent
 108                          * here. However, it may turn out that we've
 109                          * reached this commit some other way (where it
 110                          * wasn't uninteresting), in which case we need
 111                          * to mark its parents recursively too..
 112                          */
 113                         if (commit->parents)
 114                                 mark_parents_uninteresting(commit);
 115                 }
 116
 117                 /*
 118                  * A missing commit is ok iff its parent is marked
 119                  * uninteresting.
 120                  *
 121                  * We just mark such a thing parsed, so that when
 122                  * it is popped next time around, we won't be trying
 123                  * to parse it and get an error.
 124                  */
 125                 if (!has_sha1_file(commit->object.sha1))
 126                         commit->object.parsed = 1;
 127                 parents = parents->next;
 128         }
 129 }
 130
 131 static void add_pending_object_with_mode(struct rev_info *revs, struct object *obj, const char *name, unsigned mode)
 132 {
 133         if (revs->no_walk && (obj->flags & UNINTERESTING))
 134                 die("object ranges do not make sense when not walking revisions");
 135         if (revs->reflog_info && obj->type == OBJ_COMMIT &&
 136                         add_reflog_for_walk(revs->reflog_info,
 137                                 (struct commit *)obj, name))
 138                 return;
 139         add_object_array_with_mode(obj, name, &revs->pending, mode);
 140 }
 141
 142 void add_pending_object(struct rev_info *revs, struct object *obj, const char *name)
 143 {
 144         add_pending_object_with_mode(revs, obj, name, S_IFINVALID);
 145 }
 146
 147 void add_head_to_pending(struct rev_info *revs)
 148 {
 149         unsigned char sha1[20];
 150         struct object *obj;
 151         if (get_sha1("HEAD", sha1))
 152                 return;
 153         obj = parse_object(sha1);
 154         if (!obj)
 155                 return;
 156         add_pending_object(revs, obj, "HEAD");
 157 }
 158
 159 static struct object *get_reference(struct rev_info *revs, const char *name, const unsigned char *sha1, unsigned int flags)
 160 {
 161         struct object *object;
 162
 163         object = parse_object(sha1);
 164         if (!object)
 165                 die("bad object %s", name);
 166         object->flags |= flags;
 167         return object;
 168 }
 169
 170 static struct commit *handle_commit(struct rev_info *revs, struct object *object, const char *name)
 171 {
 172         unsigned long flags = object->flags;
 173
 174         /*
 175          * Tag object? Look what it points to..
 176          */
 177         while (object->type == OBJ_TAG) {
 178                 struct tag *tag = (struct tag *) object;
 179                 if (revs->tag_objects && !(flags & UNINTERESTING))
 180                         add_pending_object(revs, object, tag->tag);
 181                 if (!tag->tagged)
 182                         die("bad tag");
 183                 object = parse_object(tag->tagged->sha1);
 184                 if (!object)
 185                         die("bad object %s", sha1_to_hex(tag->tagged->sha1));
 186         }
 187
 188         /*
 189          * Commit object? Just return it, we'll do all the complex
 190          * reachability crud.
 191          */
 192         if (object->type == OBJ_COMMIT) {
 193                 struct commit *commit = (struct commit *)object;
 194                 if (parse_commit(commit) < 0)
 195                         die("unable to parse commit %s", name);
 196                 if (flags & UNINTERESTING) {
 197                         commit->object.flags |= UNINTERESTING;
 198                         mark_parents_uninteresting(commit);
 199                         revs->limited = 1;
 200                 }
 201                 return commit;
 202         }
 203
 204         /*
 205          * Tree object? Either mark it uniniteresting, or add it
 206          * to the list of objects to look at later..
 207          */
 208         if (object->type == OBJ_TREE) {
 209                 struct tree *tree = (struct tree *)object;
 210                 if (!revs->tree_objects)
 211                         return NULL;
 212                 if (flags & UNINTERESTING) {
 213                         mark_tree_uninteresting(tree);
 214                         return NULL;
 215                 }
 216                 add_pending_object(revs, object, "");
 217                 return NULL;
 218         }
 219
 220         /*
 221          * Blob object? You know the drill by now..
 222          */
 223         if (object->type == OBJ_BLOB) {
 224                 struct blob *blob = (struct blob *)object;
 225                 if (!revs->blob_objects)
 226                         return NULL;
 227                 if (flags & UNINTERESTING) {
 228                         mark_blob_uninteresting(blob);
 229                         return NULL;
 230                 }
 231                 add_pending_object(revs, object, "");
 232                 return NULL;
 233         }
 234         die("%s is unknown object", name);
 235 }
 236
 237 static int everybody_uninteresting(struct commit_list *orig)
 238 {
 239         struct commit_list *list = orig;
 240         while (list) {
 241                 struct commit *commit = list->item;
 242                 list = list->next;
 243                 if (commit->object.flags & UNINTERESTING)
 244                         continue;
 245                 return 0;
 246         }
 247         return 1;
 248 }
 249
 250 /*
 251  * The goal is to get REV_TREE_NEW as the result only if the
 252  * diff consists of all '+' (and no other changes), and
 253  * REV_TREE_DIFFERENT otherwise (of course if the trees are
 254  * the same we want REV_TREE_SAME).  That means that once we
 255  * get to REV_TREE_DIFFERENT, we do not have to look any further.
 256  */
 257 static int tree_difference = REV_TREE_SAME;
 258
 259 static void file_add_remove(struct diff_options *options,
 260                     int addremove, unsigned mode,
 261                     const unsigned char *sha1,
 262                     const char *base, const char *path)
 263 {
 264         int diff = REV_TREE_DIFFERENT;
 265
 266         /*
 267          * Is it an add of a new file? It means that the old tree
 268          * didn't have it at all, so we will turn "REV_TREE_SAME" ->
 269          * "REV_TREE_NEW", but leave any "REV_TREE_DIFFERENT" alone
 270          * (and if it already was "REV_TREE_NEW", we'll keep it
 271          * "REV_TREE_NEW" of course).
 272          */
 273         if (addremove == '+') {
 274                 diff = tree_difference;
 275                 if (diff != REV_TREE_SAME)
 276                         return;
 277                 diff = REV_TREE_NEW;
 278         }
 279         tree_difference = diff;
 280         if (tree_difference == REV_TREE_DIFFERENT)
 281                 DIFF_OPT_SET(options, HAS_CHANGES);
 282 }
 283
 284 static void file_change(struct diff_options *options,
 285                  unsigned old_mode, unsigned new_mode,
 286                  const unsigned char *old_sha1,
 287                  const unsigned char *new_sha1,
 288                  const char *base, const char *path)
 289 {
 290         tree_difference = REV_TREE_DIFFERENT;
 291         DIFF_OPT_SET(options, HAS_CHANGES);
 292 }
 293
 294 static int rev_compare_tree(struct rev_info *revs, struct tree *t1, struct tree *t2)
 295 {
 296         if (!t1)
 297                 return REV_TREE_NEW;
 298         if (!t2)
 299                 return REV_TREE_DIFFERENT;
 300         tree_difference = REV_TREE_SAME;
 301         DIFF_OPT_CLR(&revs->pruning, HAS_CHANGES);
 302         if (diff_tree_sha1(t1->object.sha1, t2->object.sha1, "",
 303                            &revs->pruning) < 0)
 304                 return REV_TREE_DIFFERENT;
 305         return tree_difference;
 306 }
 307
 308 static int rev_same_tree_as_empty(struct rev_info *revs, struct tree *t1)
 309 {
 310         int retval;
 311         void *tree;
 312         unsigned long size;
 313         struct tree_desc empty, real;
 314
 315         if (!t1)
 316                 return 0;
 317
 318         tree = read_object_with_reference(t1->object.sha1, tree_type, &size, NULL);
 319         if (!tree)
 320                 return 0;
 321         init_tree_desc(&real, tree, size);
 322         init_tree_desc(&empty, "", 0);
 323
 324         tree_difference = REV_TREE_SAME;
 325         DIFF_OPT_CLR(&revs->pruning, HAS_CHANGES);
 326         retval = diff_tree(&empty, &real, "", &revs->pruning);
 327         free(tree);
 328
 329         return retval >= 0 && (tree_difference == REV_TREE_SAME);
 330 }
 331
 332 static void try_to_simplify_commit(struct rev_info *revs, struct commit *commit)
 333 {
 334         struct commit_list **pp, *parent;
 335         int tree_changed = 0, tree_same = 0;
 336
 337         /*
 338          * If we don't do pruning, everything is interesting
 339          */
 340         if (!revs->prune)
 341                 return;
 342
 343         if (!commit->tree)
 344                 return;
 345
 346         if (!commit->parents) {
 347                 if (rev_same_tree_as_empty(revs, commit->tree))
 348                         commit->object.flags |= TREESAME;
 349                 return;
 350         }
 351
 352         /*
 353          * Normal non-merge commit? If we don't want to make the
 354          * history dense, we consider it always to be a change..
 355          */
 356         if (!revs->dense && !commit->parents->next)
 357                 return;
 358
 359         pp = &commit->parents;
 360         while ((parent = *pp) != NULL) {
 361                 struct commit *p = parent->item;
 362
 363                 if (parse_commit(p) < 0)
 364                         die("cannot simplify commit %s (because of %s)",
 365                             sha1_to_hex(commit->object.sha1),
 366                             sha1_to_hex(p->object.sha1));
 367                 switch (rev_compare_tree(revs, p->tree, commit->tree)) {
 368                 case REV_TREE_SAME:
 369                         tree_same = 1;
 370                         if (!revs->simplify_history || (p->object.flags & UNINTERESTING)) {
 371                                 /* Even if a merge with an uninteresting
 372                                  * side branch brought the entire change
 373                                  * we are interested in, we do not want
 374                                  * to lose the other branches of this
 375                                  * merge, so we just keep going.
 376                                  */
 377                                 pp = &parent->next;
 378                                 continue;
 379                         }
 380                         parent->next = NULL;
 381                         commit->parents = parent;
 382                         commit->object.flags |= TREESAME;
 383                         return;
 384
 385                 case REV_TREE_NEW:
 386                         if (revs->remove_empty_trees &&
 387                             rev_same_tree_as_empty(revs, p->tree)) {
 388                                 /* We are adding all the specified
 389                                  * paths from this parent, so the
 390                                  * history beyond this parent is not
 391                                  * interesting.  Remove its parents
 392                                  * (they are grandparents for us).
 393                                  * IOW, we pretend this parent is a
 394                                  * "root" commit.
 395                                  */
 396                                 if (parse_commit(p) < 0)
 397                                         die("cannot simplify commit %s (invalid %s)",
 398                                             sha1_to_hex(commit->object.sha1),
 399                                             sha1_to_hex(p->object.sha1));
 400                                 p->parents = NULL;
 401                         }
 402                 /* fallthrough */
 403                 case REV_TREE_DIFFERENT:
 404                         tree_changed = 1;
 405                         pp = &parent->next;
 406                         continue;
 407                 }
 408                 die("bad tree compare for commit %s", sha1_to_hex(commit->object.sha1));
 409         }
 410         if (tree_changed && !tree_same)
 411                 return;
 412         commit->object.flags |= TREESAME;
 413 }
 414
 415 static int add_parents_to_list(struct rev_info *revs, struct commit *commit, struct commit_list **list)
 416 {
 417         struct commit_list *parent = commit->parents;
 418         unsigned left_flag;
 419
 420         if (commit->object.flags & ADDED)
 421                 return 0;
 422         commit->object.flags |= ADDED;
 423
 424         /*
 425          * If the commit is uninteresting, don't try to
 426          * prune parents - we want the maximal uninteresting
 427          * set.
 428          *
 429          * Normally we haven't parsed the parent
 430          * yet, so we won't have a parent of a parent
 431          * here. However, it may turn out that we've
 432          * reached this commit some other way (where it
 433          * wasn't uninteresting), in which case we need
 434          * to mark its parents recursively too..
 435          */
 436         if (commit->object.flags & UNINTERESTING) {
 437                 while (parent) {
 438                         struct commit *p = parent->item;
 439                         parent = parent->next;
 440                         if (parse_commit(p) < 0)
 441                                 return -1;
 442                         p->object.flags |= UNINTERESTING;
 443                         if (p->parents)
 444                                 mark_parents_uninteresting(p);
 445                         if (p->object.flags & SEEN)
 446                                 continue;
 447                         p->object.flags |= SEEN;
 448                         insert_by_date(p, list);
 449                 }
 450                 return 0;
 451         }
 452
 453         /*
 454          * Ok, the commit wasn't uninteresting. Try to
 455          * simplify the commit history and find the parent
 456          * that has no differences in the path set if one exists.
 457          */
 458         try_to_simplify_commit(revs, commit);
 459
 460         if (revs->no_walk)
 461                 return 0;
 462
 463         left_flag = (commit->object.flags & SYMMETRIC_LEFT);
 464
 465         for (parent = commit->parents; parent; parent = parent->next) {
 466                 struct commit *p = parent->item;
 467
 468                 if (parse_commit(p) < 0)
 469                         return -1;
 470                 p->object.flags |= left_flag;
 471                 if (!(p->object.flags & SEEN)) {
 472                         p->object.flags |= SEEN;
 473                         insert_by_date(p, list);
 474                 }
 475                 if(revs->first_parent_only)
 476                         break;
 477         }
 478         return 0;
 479 }
 480
 481 static void cherry_pick_list(struct commit_list *list, struct rev_info *revs)
 482 {
 483         struct commit_list *p;
 484         int left_count = 0, right_count = 0;
 485         int left_first;
 486         struct patch_ids ids;
 487
 488         /* First count the commits on the left and on the right */
 489         for (p = list; p; p = p->next) {
 490                 struct commit *commit = p->item;
 491                 unsigned flags = commit->object.flags;
 492                 if (flags & BOUNDARY)
 493                         ;
 494                 else if (flags & SYMMETRIC_LEFT)
 495                         left_count++;
 496                 else
 497                         right_count++;
 498         }
 499
 500         left_first = left_count < right_count;
 501         init_patch_ids(&ids);
 502         if (revs->diffopt.nr_paths) {
 503                 ids.diffopts.nr_paths = revs->diffopt.nr_paths;
 504                 ids.diffopts.paths = revs->diffopt.paths;
 505                 ids.diffopts.pathlens = revs->diffopt.pathlens;
 506         }
 507
 508         /* Compute patch-ids for one side */
 509         for (p = list; p; p = p->next) {
 510                 struct commit *commit = p->item;
 511                 unsigned flags = commit->object.flags;
 512
 513                 if (flags & BOUNDARY)
 514                         continue;
 515                 /*
 516                  * If we have fewer left, left_first is set and we omit
 517                  * commits on the right branch in this loop.  If we have
 518                  * fewer right, we skip the left ones.
 519                  */
 520                 if (left_first != !!(flags & SYMMETRIC_LEFT))
 521                         continue;
 522                 commit->util = add_commit_patch_id(commit, &ids);
 523         }
 524
 525         /* Check the other side */
 526         for (p = list; p; p = p->next) {
 527                 struct commit *commit = p->item;
 528                 struct patch_id *id;
 529                 unsigned flags = commit->object.flags;
 530
 531                 if (flags & BOUNDARY)
 532                         continue;
 533                 /*
 534                  * If we have fewer left, left_first is set and we omit
 535                  * commits on the left branch in this loop.
 536                  */
 537                 if (left_first == !!(flags & SYMMETRIC_LEFT))
 538                         continue;
 539
 540                 /*
 541                  * Have we seen the same patch id?
 542                  */
 543                 id = has_commit_patch_id(commit, &ids);
 544                 if (!id)
 545                         continue;
 546                 id->seen = 1;
 547                 commit->object.flags |= SHOWN;
 548         }
 549
 550         /* Now check the original side for seen ones */
 551         for (p = list; p; p = p->next) {
 552                 struct commit *commit = p->item;
 553                 struct patch_id *ent;
 554
 555                 ent = commit->util;
 556                 if (!ent)
 557                         continue;
 558                 if (ent->seen)
 559                         commit->object.flags |= SHOWN;
 560                 commit->util = NULL;
 561         }
 562
 563         free_patch_ids(&ids);
 564 }
 565
 566 /* How many extra uninteresting commits we want to see.. */
 567 #define SLOP 5
 568
 569 static int still_interesting(struct commit_list *src, unsigned long date, int slop)
 570 {
 571         /*
 572          * No source list at all? We're definitely done..
 573          */
 574         if (!src)
 575                 return 0;
 576
 577         /*
 578          * Does the destination list contain entries with a date
 579          * before the source list? Definitely _not_ done.
 580          */
 581         if (date < src->item->date)
 582                 return SLOP;
 583
 584         /*
 585          * Does the source list still have interesting commits in
 586          * it? Definitely not done..
 587          */
 588         if (!everybody_uninteresting(src))
 589                 return SLOP;
 590
 591         /* Ok, we're closing in.. */
 592         return slop-1;
 593 }
 594
 595 static int limit_list(struct rev_info *revs)
 596 {
 597         int slop = SLOP;
 598         unsigned long date = ~0ul;
 599         struct commit_list *list = revs->commits;
 600         struct commit_list *newlist = NULL;
 601         struct commit_list **p = &newlist;
 602
 603         while (list) {
 604                 struct commit_list *entry = list;
 605                 struct commit *commit = list->item;
 606                 struct object *obj = &commit->object;
 607                 show_early_output_fn_t show;
 608
 609                 list = list->next;
 610                 free(entry);
 611
 612                 if (revs->max_age != -1 && (commit->date < revs->max_age))
 613                         obj->flags |= UNINTERESTING;
 614                 if (add_parents_to_list(revs, commit, &list) < 0)
 615                         return -1;
 616                 if (obj->flags & UNINTERESTING) {
 617                         mark_parents_uninteresting(commit);
 618                         if (revs->show_all)
 619                                 p = &commit_list_insert(commit, p)->next;
 620                         slop = still_interesting(list, date, slop);
 621                         if (slop)
 622                                 continue;
 623                         /* If showing all, add the whole pending list to the end */
 624                         if (revs->show_all)
 625                                 *p = list;
 626                         break;
 627                 }
 628                 if (revs->min_age != -1 && (commit->date > revs->min_age))
 629                         continue;
 630                 date = commit->date;
 631                 p = &commit_list_insert(commit, p)->next;
 632
 633                 show = show_early_output;
 634                 if (!show)
 635                         continue;
 636
 637                 show(revs, newlist);
 638                 show_early_output = NULL;
 639         }
 640         if (revs->cherry_pick)
 641                 cherry_pick_list(newlist, revs);
 642
 643         revs->commits = newlist;
 644         return 0;
 645 }
 646
 647 struct all_refs_cb {
 648         int all_flags;
 649         int warned_bad_reflog;
 650         struct rev_info *all_revs;
 651         const char *name_for_errormsg;
 652 };
 653
 654 static int handle_one_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 655 {
 656         struct all_refs_cb *cb = cb_data;
 657         struct object *object = get_reference(cb->all_revs, path, sha1,
 658                                               cb->all_flags);
 659         add_pending_object(cb->all_revs, object, path);
 660         return 0;
 661 }
 662
 663 static void handle_refs(struct rev_info *revs, unsigned flags,
 664                 int (*for_each)(each_ref_fn, void *))
 665 {
 666         struct all_refs_cb cb;
 667         cb.all_revs = revs;
 668         cb.all_flags = flags;
 669         for_each(handle_one_ref, &cb);
 670 }
 671
 672 static void handle_one_reflog_commit(unsigned char *sha1, void *cb_data)
 673 {
 674         struct all_refs_cb *cb = cb_data;
 675         if (!is_null_sha1(sha1)) {
 676                 struct object *o = parse_object(sha1);
 677                 if (o) {
 678                         o->flags |= cb->all_flags;
 679                         add_pending_object(cb->all_revs, o, "");
 680                 }
 681                 else if (!cb->warned_bad_reflog) {
 682                         warning("reflog of '%s' references pruned commits",
 683                                 cb->name_for_errormsg);
 684                         cb->warned_bad_reflog = 1;
 685                 }
 686         }
 687 }
 688
 689 static int handle_one_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
 690                 const char *email, unsigned long timestamp, int tz,
 691                 const char *message, void *cb_data)
 692 {
 693         handle_one_reflog_commit(osha1, cb_data);
 694         handle_one_reflog_commit(nsha1, cb_data);
 695         return 0;
 696 }
 697
 698 static int handle_one_reflog(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 699 {
 700         struct all_refs_cb *cb = cb_data;
 701         cb->warned_bad_reflog = 0;
 702         cb->name_for_errormsg = path;
 703         for_each_reflog_ent(path, handle_one_reflog_ent, cb_data);
 704         return 0;
 705 }
 706
 707 static void handle_reflog(struct rev_info *revs, unsigned flags)
 708 {
 709         struct all_refs_cb cb;
 710         cb.all_revs = revs;
 711         cb.all_flags = flags;
 712         for_each_reflog(handle_one_reflog, &cb);
 713 }
 714
 715 static int add_parents_only(struct rev_info *revs, const char *arg, int flags)
 716 {
 717         unsigned char sha1[20];
 718         struct object *it;
 719         struct commit *commit;
 720         struct commit_list *parents;
 721
 722         if (*arg == '^') {
 723                 flags ^= UNINTERESTING;
 724                 arg++;
 725         }
 726         if (get_sha1(arg, sha1))
 727                 return 0;
 728         while (1) {
 729                 it = get_reference(revs, arg, sha1, 0);
 730                 if (it->type != OBJ_TAG)
 731                         break;
 732                 if (!((struct tag*)it)->tagged)
 733                         return 0;
 734                 hashcpy(sha1, ((struct tag*)it)->tagged->sha1);
 735         }
 736         if (it->type != OBJ_COMMIT)
 737                 return 0;
 738         commit = (struct commit *)it;
 739         for (parents = commit->parents; parents; parents = parents->next) {
 740                 it = &parents->item->object;
 741                 it->flags |= flags;
 742                 add_pending_object(revs, it, arg);
 743         }
 744         return 1;
 745 }
 746
 747 void init_revisions(struct rev_info *revs, const char *prefix)
 748 {
 749         memset(revs, 0, sizeof(*revs));
 750
 751         revs->abbrev = DEFAULT_ABBREV;
 752         revs->ignore_merges = 1;
 753         revs->simplify_history = 1;
 754         DIFF_OPT_SET(&revs->pruning, RECURSIVE);
 755         DIFF_OPT_SET(&revs->pruning, QUIET);
 756         revs->pruning.add_remove = file_add_remove;
 757         revs->pruning.change = file_change;
 758         revs->lifo = 1;
 759         revs->dense = 1;
 760         revs->prefix = prefix;
 761         revs->max_age = -1;
 762         revs->min_age = -1;
 763         revs->skip_count = -1;
 764         revs->max_count = -1;
 765
 766         revs->commit_format = CMIT_FMT_DEFAULT;
 767
 768         diff_setup(&revs->diffopt);
 769         if (prefix && !revs->diffopt.prefix) {
 770                 revs->diffopt.prefix = prefix;
 771                 revs->diffopt.prefix_length = strlen(prefix);
 772         }
 773 }
 774
 775 static void add_pending_commit_list(struct rev_info *revs,
 776                                     struct commit_list *commit_list,
 777                                     unsigned int flags)
 778 {
 779         while (commit_list) {
 780                 struct object *object = &commit_list->item->object;
 781                 object->flags |= flags;
 782                 add_pending_object(revs, object, sha1_to_hex(object->sha1));
 783                 commit_list = commit_list->next;
 784         }
 785 }
 786
 787 static void prepare_show_merge(struct rev_info *revs)
 788 {
 789         struct commit_list *bases;
 790         struct commit *head, *other;
 791         unsigned char sha1[20];
 792         const char **prune = NULL;
 793         int i, prune_num = 1; /* counting terminating NULL */
 794
 795         if (get_sha1("HEAD", sha1) || !(head = lookup_commit(sha1)))
 796                 die("--merge without HEAD?");
 797         if (get_sha1("MERGE_HEAD", sha1) || !(other = lookup_commit(sha1)))
 798                 die("--merge without MERGE_HEAD?");
 799         add_pending_object(revs, &head->object, "HEAD");
 800         add_pending_object(revs, &other->object, "MERGE_HEAD");
 801         bases = get_merge_bases(head, other, 1);
 802         add_pending_commit_list(revs, bases, UNINTERESTING);
 803         free_commit_list(bases);
 804         head->object.flags |= SYMMETRIC_LEFT;
 805
 806         if (!active_nr)
 807                 read_cache();
 808         for (i = 0; i < active_nr; i++) {
 809                 struct cache_entry *ce = active_cache[i];
 810                 if (!ce_stage(ce))
 811                         continue;
 812                 if (ce_path_match(ce, revs->prune_data)) {
 813                         prune_num++;
 814                         prune = xrealloc(prune, sizeof(*prune) * prune_num);
 815                         prune[prune_num-2] = ce->name;
 816                         prune[prune_num-1] = NULL;
 817                 }
 818                 while ((i+1 < active_nr) &&
 819                        ce_same_name(ce, active_cache[i+1]))
 820                         i++;
 821         }
 822         revs->prune_data = prune;
 823         revs->limited = 1;
 824 }
 825
 826 int handle_revision_arg(const char *arg, struct rev_info *revs,
 827                         int flags,
 828                         int cant_be_filename)
 829 {
 830         unsigned mode;
 831         char *dotdot;
 832         struct object *object;
 833         unsigned char sha1[20];
 834         int local_flags;
 835
 836         dotdot = strstr(arg, "..");
 837         if (dotdot) {
 838                 unsigned char from_sha1[20];
 839                 const char *next = dotdot + 2;
 840                 const char *this = arg;
 841                 int symmetric = *next == '.';
 842                 unsigned int flags_exclude = flags ^ UNINTERESTING;
 843
 844                 *dotdot = 0;
 845                 next += symmetric;
 846
 847                 if (!*next)
 848                         next = "HEAD";
 849                 if (dotdot == arg)
 850                         this = "HEAD";
 851                 if (!get_sha1(this, from_sha1) &&
 852                     !get_sha1(next, sha1)) {
 853                         struct commit *a, *b;
 854                         struct commit_list *exclude;
 855
 856                         a = lookup_commit_reference(from_sha1);
 857                         b = lookup_commit_reference(sha1);
 858                         if (!a || !b) {
 859                                 die(symmetric ?
 860                                     "Invalid symmetric difference expression %s...%s" :
 861                                     "Invalid revision range %s..%s",
 862                                     arg, next);
 863                         }
 864
 865                         if (!cant_be_filename) {
 866                                 *dotdot = '.';
 867                                 verify_non_filename(revs->prefix, arg);
 868                         }
 869
 870                         if (symmetric) {
 871                                 exclude = get_merge_bases(a, b, 1);
 872                                 add_pending_commit_list(revs, exclude,
 873                                                         flags_exclude);
 874                                 free_commit_list(exclude);
 875                                 a->object.flags |= flags | SYMMETRIC_LEFT;
 876                         } else
 877                                 a->object.flags |= flags_exclude;
 878                         b->object.flags |= flags;
 879                         add_pending_object(revs, &a->object, this);
 880                         add_pending_object(revs, &b->object, next);
 881                         return 0;
 882                 }
 883                 *dotdot = '.';
 884         }
 885         dotdot = strstr(arg, "^@");
 886         if (dotdot && !dotdot[2]) {
 887                 *dotdot = 0;
 888                 if (add_parents_only(revs, arg, flags))
 889                         return 0;
 890                 *dotdot = '^';
 891         }
 892         dotdot = strstr(arg, "^!");
 893         if (dotdot && !dotdot[2]) {
 894                 *dotdot = 0;
 895                 if (!add_parents_only(revs, arg, flags ^ UNINTERESTING))
 896                         *dotdot = '^';
 897         }
 898
 899         local_flags = 0;
 900         if (*arg == '^') {
 901                 local_flags = UNINTERESTING;
 902                 arg++;
 903         }
 904         if (get_sha1_with_mode(arg, sha1, &mode))
 905                 return -1;
 906         if (!cant_be_filename)
 907                 verify_non_filename(revs->prefix, arg);
 908         object = get_reference(revs, arg, sha1, flags ^ local_flags);
 909         add_pending_object_with_mode(revs, object, arg, mode);
 910         return 0;
 911 }
 912
 913 static void add_grep(struct rev_info *revs, const char *ptn, enum grep_pat_token what)
 914 {
 915         if (!revs->grep_filter) {
 916                 struct grep_opt *opt = xcalloc(1, sizeof(*opt));
 917                 opt->status_only = 1;
 918                 opt->pattern_tail = &(opt->pattern_list);
 919                 opt->regflags = REG_NEWLINE;
 920                 revs->grep_filter = opt;
 921         }
 922         append_grep_pattern(revs->grep_filter, ptn,
 923                             "command line", 0, what);
 924 }
 925
 926 static void add_header_grep(struct rev_info *revs, const char *field, const char *pattern)
 927 {
 928         char *pat;
 929         const char *prefix;
 930         int patlen, fldlen;
 931
 932         fldlen = strlen(field);
 933         patlen = strlen(pattern);
 934         pat = xmalloc(patlen + fldlen + 10);
 935         prefix = ".*";
 936         if (*pattern == '^') {
 937                 prefix = "";
 938                 pattern++;
 939         }
 940         sprintf(pat, "^%s %s%s", field, prefix, pattern);
 941         add_grep(revs, pat, GREP_PATTERN_HEAD);
 942 }
 943
 944 static void add_message_grep(struct rev_info *revs, const char *pattern)
 945 {
 946         add_grep(revs, pattern, GREP_PATTERN_BODY);
 947 }
 948
 949 static void add_ignore_packed(struct rev_info *revs, const char *name)
 950 {
 951         int num = ++revs->num_ignore_packed;
 952
 953         revs->ignore_packed = xrealloc(revs->ignore_packed,
 954                                        sizeof(const char **) * (num + 1));
 955         revs->ignore_packed[num-1] = name;
 956         revs->ignore_packed[num] = NULL;
 957 }
 958
 959 /*
 960  * Parse revision information, filling in the "rev_info" structure,
 961  * and removing the used arguments from the argument list.
 962  *
 963  * Returns the number of arguments left that weren't recognized
 964  * (which are also moved to the head of the argument list)
 965  */
 966 int setup_revisions(int argc, const char **argv, struct rev_info *revs, const char *def)
 967 {
 968         int i, flags, seen_dashdash, show_merge;
 969         const char **unrecognized = argv + 1;
 970         int left = 1;
 971         int all_match = 0;
 972         int regflags = 0;
 973         int fixed = 0;
 974
 975         /* First, search for "--" */
 976         seen_dashdash = 0;
 977         for (i = 1; i < argc; i++) {
 978                 const char *arg = argv[i];
 979                 if (strcmp(arg, "--"))
 980                         continue;
 981                 argv[i] = NULL;
 982                 argc = i;
 983                 if (argv[i + 1])
 984                         revs->prune_data = get_pathspec(revs->prefix, argv + i + 1);
 985                 seen_dashdash = 1;
 986                 break;
 987         }
 988
 989         flags = show_merge = 0;
 990         for (i = 1; i < argc; i++) {
 991                 const char *arg = argv[i];
 992                 if (*arg == '-') {
 993                         int opts;
 994                         if (!prefixcmp(arg, "--max-count=")) {
 995                                 revs->max_count = atoi(arg + 12);
 996                                 continue;
 997                         }
 998                         if (!prefixcmp(arg, "--skip=")) {
 999                                 revs->skip_count = atoi(arg + 7);
1000                                 continue;
1001                         }
1002                         /* accept -<digit>, like traditional "head" */
1003                         if ((*arg == '-') && isdigit(arg[1])) {
1004                                 revs->max_count = atoi(arg + 1);
1005                                 continue;
1006                         }
1007                         if (!strcmp(arg, "-n")) {
1008                                 if (argc <= i + 1)
1009                                         die("-n requires an argument");
1010                                 revs->max_count = atoi(argv[++i]);
1011                                 continue;
1012                         }
1013                         if (!prefixcmp(arg, "-n")) {
1014                                 revs->max_count = atoi(arg + 2);
1015                                 continue;
1016                         }
1017                         if (!prefixcmp(arg, "--max-age=")) {
1018                                 revs->max_age = atoi(arg + 10);
1019                                 continue;
1020                         }
1021                         if (!prefixcmp(arg, "--since=")) {
1022                                 revs->max_age = approxidate(arg + 8);
1023                                 continue;
1024                         }
1025                         if (!prefixcmp(arg, "--after=")) {
1026                                 revs->max_age = approxidate(arg + 8);
1027                                 continue;
1028                         }
1029                         if (!prefixcmp(arg, "--min-age=")) {
1030                                 revs->min_age = atoi(arg + 10);
1031                                 continue;
1032                         }
1033                         if (!prefixcmp(arg, "--before=")) {
1034                                 revs->min_age = approxidate(arg + 9);
1035                                 continue;
1036                         }
1037                         if (!prefixcmp(arg, "--until=")) {
1038                                 revs->min_age = approxidate(arg + 8);
1039                                 continue;
1040                         }
1041                         if (!strcmp(arg, "--all")) {
1042                                 handle_refs(revs, flags, for_each_ref);
1043                                 continue;
1044                         }
1045                         if (!strcmp(arg, "--branches")) {
1046                                 handle_refs(revs, flags, for_each_branch_ref);
1047                                 continue;
1048                         }
1049                         if (!strcmp(arg, "--tags")) {
1050                                 handle_refs(revs, flags, for_each_tag_ref);
1051                                 continue;
1052                         }
1053                         if (!strcmp(arg, "--remotes")) {
1054                                 handle_refs(revs, flags, for_each_remote_ref);
1055                                 continue;
1056                         }
1057                         if (!strcmp(arg, "--first-parent")) {
1058                                 revs->first_parent_only = 1;
1059                                 continue;
1060                         }
1061                         if (!strcmp(arg, "--reflog")) {
1062                                 handle_reflog(revs, flags);
1063                                 continue;
1064                         }
1065                         if (!strcmp(arg, "-g") ||
1066                                         !strcmp(arg, "--walk-reflogs")) {
1067                                 init_reflog_walk(&revs->reflog_info);
1068                                 continue;
1069                         }
1070                         if (!strcmp(arg, "--not")) {
1071                                 flags ^= UNINTERESTING;
1072                                 continue;
1073                         }
1074                         if (!strcmp(arg, "--default")) {
1075                                 if (++i >= argc)
1076                                         die("bad --default argument");
1077                                 def = argv[i];
1078                                 continue;
1079                         }
1080                         if (!strcmp(arg, "--merge")) {
1081                                 show_merge = 1;
1082                                 continue;
1083                         }
1084                         if (!strcmp(arg, "--topo-order")) {
1085                                 revs->lifo = 1;
1086                                 revs->topo_order = 1;
1087                                 continue;
1088                         }
1089                         if (!strcmp(arg, "--date-order")) {
1090                                 revs->lifo = 0;
1091                                 revs->topo_order = 1;
1092                                 continue;
1093                         }
1094                         if (!prefixcmp(arg, "--early-output")) {
1095                                 int count = 100;
1096                                 switch (arg[14]) {
1097                                 case '=':
1098                                         count = atoi(arg+15);
1099                                         /* Fallthrough */
1100                                 case 0:
1101                                         revs->topo_order = 1;
1102                                         revs->early_output = count;
1103                                         continue;
1104                                 }
1105                         }
1106                         if (!strcmp(arg, "--parents")) {
1107                                 revs->rewrite_parents = 1;
1108                                 revs->print_parents = 1;
1109                                 continue;
1110                         }
1111                         if (!strcmp(arg, "--dense")) {
1112                                 revs->dense = 1;
1113                                 continue;
1114                         }
1115                         if (!strcmp(arg, "--sparse")) {
1116                                 revs->dense = 0;
1117                                 continue;
1118                         }
1119                         if (!strcmp(arg, "--show-all")) {
1120                                 revs->show_all = 1;
1121                                 continue;
1122                         }
1123                         if (!strcmp(arg, "--remove-empty")) {
1124                                 revs->remove_empty_trees = 1;
1125                                 continue;
1126                         }
1127                         if (!strcmp(arg, "--no-merges")) {
1128                                 revs->no_merges = 1;
1129                                 continue;
1130                         }
1131                         if (!strcmp(arg, "--boundary")) {
1132                                 revs->boundary = 1;
1133                                 continue;
1134                         }
1135                         if (!strcmp(arg, "--left-right")) {
1136                                 revs->left_right = 1;
1137                                 continue;
1138                         }
1139                         if (!strcmp(arg, "--cherry-pick")) {
1140                                 revs->cherry_pick = 1;
1141                                 revs->limited = 1;
1142                                 continue;
1143                         }
1144                         if (!strcmp(arg, "--objects")) {
1145                                 revs->tag_objects = 1;
1146                                 revs->tree_objects = 1;
1147                                 revs->blob_objects = 1;
1148                                 continue;
1149                         }
1150                         if (!strcmp(arg, "--objects-edge")) {
1151                                 revs->tag_objects = 1;
1152                                 revs->tree_objects = 1;
1153                                 revs->blob_objects = 1;
1154                                 revs->edge_hint = 1;
1155                                 continue;
1156                         }
1157                         if (!strcmp(arg, "--unpacked")) {
1158                                 revs->unpacked = 1;
1159                                 free(revs->ignore_packed);
1160                                 revs->ignore_packed = NULL;
1161                                 revs->num_ignore_packed = 0;
1162                                 continue;
1163                         }
1164                         if (!prefixcmp(arg, "--unpacked=")) {
1165                                 revs->unpacked = 1;
1166                                 add_ignore_packed(revs, arg+11);
1167                                 continue;
1168                         }
1169                         if (!strcmp(arg, "-r")) {
1170                                 revs->diff = 1;
1171                                 DIFF_OPT_SET(&revs->diffopt, RECURSIVE);
1172                                 continue;
1173                         }
1174                         if (!strcmp(arg, "-t")) {
1175                                 revs->diff = 1;
1176                                 DIFF_OPT_SET(&revs->diffopt, RECURSIVE);
1177                                 DIFF_OPT_SET(&revs->diffopt, TREE_IN_RECURSIVE);
1178                                 continue;
1179                         }
1180                         if (!strcmp(arg, "-m")) {
1181                                 revs->ignore_merges = 0;
1182                                 continue;
1183                         }
1184                         if (!strcmp(arg, "-c")) {
1185                                 revs->diff = 1;
1186                                 revs->dense_combined_merges = 0;
1187                                 revs->combine_merges = 1;
1188                                 continue;
1189                         }
1190                         if (!strcmp(arg, "--cc")) {
1191                                 revs->diff = 1;
1192                                 revs->dense_combined_merges = 1;
1193                                 revs->combine_merges = 1;
1194                                 continue;
1195                         }
1196                         if (!strcmp(arg, "-v")) {
1197                                 revs->verbose_header = 1;
1198                                 continue;
1199                         }
1200                         if (!prefixcmp(arg, "--pretty")) {
1201                                 revs->verbose_header = 1;
1202                                 get_commit_format(arg+8, revs);
1203                                 continue;
1204                         }
1205                         if (!prefixcmp(arg, "--graph")) {
1206                                 revs->topo_order = 1;
1207                                 revs->rewrite_parents = 1;
1208                                 revs->graph = graph_init(revs);
1209                                 continue;
1210                         }
1211                         if (!strcmp(arg, "--root")) {
1212                                 revs->show_root_diff = 1;
1213                                 continue;
1214                         }
1215                         if (!strcmp(arg, "--no-commit-id")) {
1216                                 revs->no_commit_id = 1;
1217                                 continue;
1218                         }
1219                         if (!strcmp(arg, "--always")) {
1220                                 revs->always_show_header = 1;
1221                                 continue;
1222                         }
1223                         if (!strcmp(arg, "--no-abbrev")) {
1224                                 revs->abbrev = 0;
1225                                 continue;
1226                         }
1227                         if (!strcmp(arg, "--abbrev")) {
1228                                 revs->abbrev = DEFAULT_ABBREV;
1229                                 continue;
1230                         }
1231                         if (!prefixcmp(arg, "--abbrev=")) {
1232                                 revs->abbrev = strtoul(arg + 9, NULL, 10);
1233                                 if (revs->abbrev < MINIMUM_ABBREV)
1234                                         revs->abbrev = MINIMUM_ABBREV;
1235                                 else if (revs->abbrev > 40)
1236                                         revs->abbrev = 40;
1237                                 continue;
1238                         }
1239                         if (!strcmp(arg, "--abbrev-commit")) {
1240                                 revs->abbrev_commit = 1;
1241                                 continue;
1242                         }
1243                         if (!strcmp(arg, "--full-diff")) {
1244                                 revs->diff = 1;
1245                                 revs->full_diff = 1;
1246                                 continue;
1247                         }
1248                         if (!strcmp(arg, "--full-history")) {
1249                                 revs->simplify_history = 0;
1250                                 continue;
1251                         }
1252                         if (!strcmp(arg, "--relative-date")) {
1253                                 revs->date_mode = DATE_RELATIVE;
1254                                 continue;
1255                         }
1256                         if (!strncmp(arg, "--date=", 7)) {
1257                                 revs->date_mode = parse_date_format(arg + 7);
1258                                 continue;
1259                         }
1260                         if (!strcmp(arg, "--log-size")) {
1261                                 revs->show_log_size = 1;
1262                                 continue;
1263                         }
1264
1265                         /*
1266                          * Grepping the commit log
1267                          */
1268                         if (!prefixcmp(arg, "--author=")) {
1269                                 add_header_grep(revs, "author", arg+9);
1270                                 continue;
1271                         }
1272                         if (!prefixcmp(arg, "--committer=")) {
1273                                 add_header_grep(revs, "committer", arg+12);
1274                                 continue;
1275                         }
1276                         if (!prefixcmp(arg, "--grep=")) {
1277                                 add_message_grep(revs, arg+7);
1278                                 continue;
1279                         }
1280                         if (!strcmp(arg, "--extended-regexp") ||
1281                             !strcmp(arg, "-E")) {
1282                                 regflags |= REG_EXTENDED;
1283                                 continue;
1284                         }
1285                         if (!strcmp(arg, "--regexp-ignore-case") ||
1286                             !strcmp(arg, "-i")) {
1287                                 regflags |= REG_ICASE;
1288                                 continue;
1289                         }
1290                         if (!strcmp(arg, "--fixed-strings") ||
1291                             !strcmp(arg, "-F")) {
1292                                 fixed = 1;
1293                                 continue;
1294                         }
1295                         if (!strcmp(arg, "--all-match")) {
1296                                 all_match = 1;
1297                                 continue;
1298                         }
1299                         if (!prefixcmp(arg, "--encoding=")) {
1300                                 arg += 11;
1301                                 if (strcmp(arg, "none"))
1302                                         git_log_output_encoding = xstrdup(arg);
1303                                 else
1304                                         git_log_output_encoding = "";
1305                                 continue;
1306                         }
1307                         if (!strcmp(arg, "--reverse")) {
1308                                 revs->reverse ^= 1;
1309                                 continue;
1310                         }
1311                         if (!strcmp(arg, "--no-walk")) {
1312                                 revs->no_walk = 1;
1313                                 continue;
1314                         }
1315                         if (!strcmp(arg, "--do-walk")) {
1316                                 revs->no_walk = 0;
1317                                 continue;
1318                         }
1319
1320                         opts = diff_opt_parse(&revs->diffopt, argv+i, argc-i);
1321                         if (opts > 0) {
1322                                 i += opts - 1;
1323                                 continue;
1324                         }
1325                         *unrecognized++ = arg;
1326                         left++;
1327                         continue;
1328                 }
1329
1330                 if (handle_revision_arg(arg, revs, flags, seen_dashdash)) {
1331                         int j;
1332                         if (seen_dashdash || *arg == '^')
1333                                 die("bad revision '%s'", arg);
1334
1335                         /* If we didn't have a "--":
1336                          * (1) all filenames must exist;
1337                          * (2) all rev-args must not be interpretable
1338                          *     as a valid filename.
1339                          * but the latter we have checked in the main loop.
1340                          */
1341                         for (j = i; j < argc; j++)
1342                                 verify_filename(revs->prefix, argv[j]);
1343
1344                         revs->prune_data = get_pathspec(revs->prefix,
1345                                                         argv + i);
1346                         break;
1347                 }
1348         }
1349
1350         if (revs->grep_filter) {
1351                 revs->grep_filter->regflags |= regflags;
1352                 revs->grep_filter->fixed = fixed;
1353         }
1354
1355         if (show_merge)
1356                 prepare_show_merge(revs);
1357         if (def && !revs->pending.nr) {
1358                 unsigned char sha1[20];
1359                 struct object *object;
1360                 unsigned mode;
1361                 if (get_sha1_with_mode(def, sha1, &mode))
1362                         die("bad default revision '%s'", def);
1363                 object = get_reference(revs, def, sha1, 0);
1364                 add_pending_object_with_mode(revs, object, def, mode);
1365         }
1366
1367         /* Did the user ask for any diff output? Run the diff! */
1368         if (revs->diffopt.output_format & ~DIFF_FORMAT_NO_OUTPUT)
1369                 revs->diff = 1;
1370
1371         /* Pickaxe, diff-filter and rename following need diffs */
1372         if (revs->diffopt.pickaxe ||
1373             revs->diffopt.filter ||
1374             DIFF_OPT_TST(&revs->diffopt, FOLLOW_RENAMES))
1375                 revs->diff = 1;
1376
1377         if (revs->topo_order)
1378                 revs->limited = 1;
1379
1380         if (revs->prune_data) {
1381                 diff_tree_setup_paths(revs->prune_data, &revs->pruning);
1382                 /* Can't prune commits with rename following: the paths change.. */
1383                 if (!DIFF_OPT_TST(&revs->diffopt, FOLLOW_RENAMES))
1384                         revs->prune = 1;
1385                 if (!revs->full_diff)
1386                         diff_tree_setup_paths(revs->prune_data, &revs->diffopt);
1387         }
1388         if (revs->combine_merges) {
1389                 revs->ignore_merges = 0;
1390                 if (revs->dense_combined_merges && !revs->diffopt.output_format)
1391                         revs->diffopt.output_format = DIFF_FORMAT_PATCH;
1392         }
1393         revs->diffopt.abbrev = revs->abbrev;
1394         if (diff_setup_done(&revs->diffopt) < 0)
1395                 die("diff_setup_done failed");
1396
1397         if (revs->grep_filter) {
1398                 revs->grep_filter->all_match = all_match;
1399                 compile_grep_patterns(revs->grep_filter);
1400         }
1401
1402         if (revs->reverse && revs->reflog_info)
1403                 die("cannot combine --reverse with --walk-reflogs");
1404
1405         /*
1406          * Limitations on the graph functionality
1407          */
1408         if (revs->reverse && revs->graph)
1409                 die("cannot combine --reverse with --graph");
1410
1411         if (revs->reflog_info && revs->graph)
1412                 die("cannot combine --walk-reflogs with --graph");
1413
1414         return left;
1415 }
1416
1417 int prepare_revision_walk(struct rev_info *revs)
1418 {
1419         int nr = revs->pending.nr;
1420         struct object_array_entry *e, *list;
1421
1422         e = list = revs->pending.objects;
1423         revs->pending.nr = 0;
1424         revs->pending.alloc = 0;
1425         revs->pending.objects = NULL;
1426         while (--nr >= 0) {
1427                 struct commit *commit = handle_commit(revs, e->item, e->name);
1428                 if (commit) {
1429                         if (!(commit->object.flags & SEEN)) {
1430                                 commit->object.flags |= SEEN;
1431                                 insert_by_date(commit, &revs->commits);
1432                         }
1433                 }
1434                 e++;
1435         }
1436         free(list);
1437
1438         if (revs->no_walk)
1439                 return 0;
1440         if (revs->limited)
1441                 if (limit_list(revs) < 0)
1442                         return -1;
1443         if (revs->topo_order)
1444                 sort_in_topological_order(&revs->commits, revs->lifo);
1445         return 0;
1446 }
1447
1448 enum rewrite_result {
1449         rewrite_one_ok,
1450         rewrite_one_noparents,
1451         rewrite_one_error,
1452 };
1453
1454 static enum rewrite_result rewrite_one(struct rev_info *revs, struct commit **pp)
1455 {
1456         for (;;) {
1457                 struct commit *p = *pp;
1458                 if (!revs->limited)
1459                         if (add_parents_to_list(revs, p, &revs->commits) < 0)
1460                                 return rewrite_one_error;
1461                 if (p->parents && p->parents->next)
1462                         return rewrite_one_ok;
1463                 if (p->object.flags & UNINTERESTING)
1464                         return rewrite_one_ok;
1465                 if (!(p->object.flags & TREESAME))
1466                         return rewrite_one_ok;
1467                 if (!p->parents)
1468                         return rewrite_one_noparents;
1469                 *pp = p->parents->item;
1470         }
1471 }
1472
1473 static void remove_duplicate_parents(struct commit *commit)
1474 {
1475         struct commit_list **pp, *p;
1476
1477         /* Examine existing parents while marking ones we have seen... */
1478         pp = &commit->parents;
1479         while ((p = *pp) != NULL) {
1480                 struct commit *parent = p->item;
1481                 if (parent->object.flags & TMP_MARK) {
1482                         *pp = p->next;
1483                         continue;
1484                 }
1485                 parent->object.flags |= TMP_MARK;
1486                 pp = &p->next;
1487         }
1488         /* ... and clear the temporary mark */
1489         for (p = commit->parents; p; p = p->next)
1490                 p->item->object.flags &= ~TMP_MARK;
1491 }
1492
1493 static int rewrite_parents(struct rev_info *revs, struct commit *commit)
1494 {
1495         struct commit_list **pp = &commit->parents;
1496         while (*pp) {
1497                 struct commit_list *parent = *pp;
1498                 switch (rewrite_one(revs, &parent->item)) {
1499                 case rewrite_one_ok:
1500                         break;
1501                 case rewrite_one_noparents:
1502                         *pp = parent->next;
1503                         continue;
1504                 case rewrite_one_error:
1505                         return -1;
1506                 }
1507                 pp = &parent->next;
1508         }
1509         remove_duplicate_parents(commit);
1510         return 0;
1511 }
1512
1513 static int commit_match(struct commit *commit, struct rev_info *opt)
1514 {
1515         if (!opt->grep_filter)
1516                 return 1;
1517         return grep_buffer(opt->grep_filter,
1518                            NULL, /* we say nothing, not even filename */
1519                            commit->buffer, strlen(commit->buffer));
1520 }
1521
1522 enum commit_action simplify_commit(struct rev_info *revs, struct commit *commit)
1523 {
1524         if (commit->object.flags & SHOWN)
1525                 return commit_ignore;
1526         if (revs->unpacked && has_sha1_pack(commit->object.sha1, revs->ignore_packed))
1527                 return commit_ignore;
1528         if (revs->show_all)
1529                 return commit_show;
1530         if (commit->object.flags & UNINTERESTING)
1531                 return commit_ignore;
1532         if (revs->min_age != -1 && (commit->date > revs->min_age))
1533                 return commit_ignore;
1534         if (revs->no_merges && commit->parents && commit->parents->next)
1535                 return commit_ignore;
1536         if (!commit_match(commit, revs))
1537                 return commit_ignore;
1538         if (revs->prune && revs->dense) {
1539                 /* Commit without changes? */
1540                 if (commit->object.flags & TREESAME) {
1541                         /* drop merges unless we want parenthood */
1542                         if (!revs->rewrite_parents)
1543                                 return commit_ignore;
1544                         /* non-merge - always ignore it */
1545                         if (!commit->parents || !commit->parents->next)
1546                                 return commit_ignore;
1547                 }
1548                 if (revs->rewrite_parents && rewrite_parents(revs, commit) < 0)
1549                         return commit_error;
1550         }
1551         return commit_show;
1552 }
1553
1554 static struct commit *get_revision_1(struct rev_info *revs)
1555 {
1556         if (!revs->commits)
1557                 return NULL;
1558
1559         do {
1560                 struct commit_list *entry = revs->commits;
1561                 struct commit *commit = entry->item;
1562
1563                 revs->commits = entry->next;
1564                 free(entry);
1565
1566                 if (revs->reflog_info)
1567                         fake_reflog_parent(revs->reflog_info, commit);
1568
1569                 /*
1570                  * If we haven't done the list limiting, we need to look at
1571                  * the parents here. We also need to do the date-based limiting
1572                  * that we'd otherwise have done in limit_list().
1573                  */
1574                 if (!revs->limited) {
1575                         if (revs->max_age != -1 &&
1576                             (commit->date < revs->max_age))
1577                                 continue;
1578                         if (add_parents_to_list(revs, commit, &revs->commits) < 0)
1579                                 return NULL;
1580                 }
1581
1582                 switch (simplify_commit(revs, commit)) {
1583                 case commit_ignore:
1584                         continue;
1585                 case commit_error:
1586                         return NULL;
1587                 default:
1588                         return commit;
1589                 }
1590         } while (revs->commits);
1591         return NULL;
1592 }
1593
1594 static void gc_boundary(struct object_array *array)
1595 {
1596         unsigned nr = array->nr;
1597         unsigned alloc = array->alloc;
1598         struct object_array_entry *objects = array->objects;
1599
1600         if (alloc <= nr) {
1601                 unsigned i, j;
1602                 for (i = j = 0; i < nr; i++) {
1603                         if (objects[i].item->flags & SHOWN)
1604                                 continue;
1605                         if (i != j)
1606                                 objects[j] = objects[i];
1607                         j++;
1608                 }
1609                 for (i = j; i < nr; i++)
1610                         objects[i].item = NULL;
1611                 array->nr = j;
1612         }
1613 }
1614
1615 static struct commit *get_revision_internal(struct rev_info *revs)
1616 {
1617         struct commit *c = NULL;
1618         struct commit_list *l;
1619
1620         if (revs->boundary == 2) {
1621                 unsigned i;
1622                 struct object_array *array = &revs->boundary_commits;
1623                 struct object_array_entry *objects = array->objects;
1624                 for (i = 0; i < array->nr; i++) {
1625                         c = (struct commit *)(objects[i].item);
1626                         if (!c)
1627                                 continue;
1628                         if (!(c->object.flags & CHILD_SHOWN))
1629                                 continue;
1630                         if (!(c->object.flags & SHOWN))
1631                                 break;
1632                 }
1633                 if (array->nr <= i)
1634                         return NULL;
1635
1636                 c->object.flags |= SHOWN | BOUNDARY;
1637                 return c;
1638         }
1639
1640         if (revs->reverse) {
1641                 int limit = -1;
1642
1643                 if (0 <= revs->max_count) {
1644                         limit = revs->max_count;
1645                         if (0 < revs->skip_count)
1646                                 limit += revs->skip_count;
1647                 }
1648                 l = NULL;
1649                 while ((c = get_revision_1(revs))) {
1650                         commit_list_insert(c, &l);
1651                         if ((0 < limit) && !--limit)
1652                                 break;
1653                 }
1654                 revs->commits = l;
1655                 revs->reverse = 0;
1656                 revs->max_count = -1;
1657                 c = NULL;
1658         }
1659
1660         /*
1661          * Now pick up what they want to give us
1662          */
1663         c = get_revision_1(revs);
1664         if (c) {
1665                 while (0 < revs->skip_count) {
1666                         revs->skip_count--;
1667                         c = get_revision_1(revs);
1668                         if (!c)
1669                                 break;
1670                 }
1671         }
1672
1673         /*
1674          * Check the max_count.
1675          */
1676         switch (revs->max_count) {
1677         case -1:
1678                 break;
1679         case 0:
1680                 c = NULL;
1681                 break;
1682         default:
1683                 revs->max_count--;
1684         }
1685
1686         if (c)
1687                 c->object.flags |= SHOWN;
1688
1689         if (!revs->boundary) {
1690                 return c;
1691         }
1692
1693         if (!c) {
1694                 /*
1695                  * get_revision_1() runs out the commits, and
1696                  * we are done computing the boundaries.
1697                  * switch to boundary commits output mode.
1698                  */
1699                 revs->boundary = 2;
1700                 return get_revision_internal(revs);
1701         }
1702
1703         /*
1704          * boundary commits are the commits that are parents of the
1705          * ones we got from get_revision_1() but they themselves are
1706          * not returned from get_revision_1().  Before returning
1707          * 'c', we need to mark its parents that they could be boundaries.
1708          */
1709
1710         for (l = c->parents; l; l = l->next) {
1711                 struct object *p;
1712                 p = &(l->item->object);
1713                 if (p->flags & (CHILD_SHOWN | SHOWN))
1714                         continue;
1715                 p->flags |= CHILD_SHOWN;
1716                 gc_boundary(&revs->boundary_commits);
1717                 add_object_array(p, NULL, &revs->boundary_commits);
1718         }
1719
1720         return c;
1721 }
1722
1723 struct commit *get_revision(struct rev_info *revs)
1724 {
1725         struct commit *c = get_revision_internal(revs);
1726         if (c && revs->graph)
1727                 graph_update(revs->graph, c);
1728         return c;
1729 }